Understanding hooks

A hook is essentially just a listener for which we've registered a callback function. These callback functions expect a single parameter: a hash that provides some context to the function. The contents of the hash depend on what type of hook is being evaluated.

There are four basic categories of hooks available in Redmine:

For view and controller hooks, the context hash contains the following fields as well as data specific to the hook being used:

To quickly build the hook list for the version of Redmine you have installed, run the following commands:

cd /path/to/redmine/app
grep -r call_hook *

By doing this from the app directory, we prune out any results from the hook class definition or any of the test files.

Redmine has many hooks registered throughout the codebase by means of the call_hook method, whose syntax is as follows:

call_hook(hook, context={})

For example, the partial /path/to/redmine/app/views/issues/_form.html.erb contains the following hook declaration:

<%= call_hook(:view_issues_form_details_bottom, { :issue => @issue, :form => f }) %>